The present invention relates to a process for enhancing the concentration of one component contained in a multi-component gas and, more particularly, to a process for enriching air by increasing the concentration of oxygen therein.
Oxygen-enriched air, as opposed to pure oxygen, is often sought by industry in order to improve combustion or, more recently, to enhance processes in biotechnology. Heretofore, oxygen-enriched air has been obtained by either mixing air with pure oxygen produced by well known cryogenic techniques or, alternatively, by pressure-swing adsorption techniques.
In conventional pressure-swing techniques, air under pressure is passed through a fixed bed adsorption system. Typically, an adsorbent such as a molecular sieve is used, the sieve preferentially adsorbing nitrogen. The gas discharged from the bed is thus higher in oxygen content than that being fed into the bed. After the adsorption, the pressure is reduced to atmospheric or even sub-atmospheric levels, and the nitrogen is desorbed from the bed. The bed is then returned to the nitrogen adsorption cycle.
The above-described technique is suitable for producing relatively small quantities of enriched air so long as the system remains relatively simple. However, as the system becomes more complex or if a higher degree of enrichment is required, the pressure-swing techniques as well as any other techniques utilizing fixed bed systems become unduly complicated and expensive to run.
Other available air enrichment systems, such as membrane separation systems, often do not require as complicated a set-up but are nonetheless disadvantageous due to the limited amounts of air which may be treated therewith.